Fixing apparatus and image forming apparatus

Abstract

The fixing apparatus includes: a fixing member having base and conductive layers and fixing a toner onto a recording medium when the conductive layer is heated by electromagnetic induction; a magnetic field generating member generating an alternating-current magnetic field crossing the conductive layer; and a magnetic field inducing member arranged so as to face the magnetic field generating member across the fixing member, and inducing the magnetic field into itself or allowing the magnetic field to go through the member. The base layer and the magnetic field inducing member each contain a material having a magnetic permeability change onset temperature in a range from not less than a heating preset temperature of the fixing member to not more than a heatproof temperature of the fixing member. A thickness of the base layer is smaller than a skin depth of the layer at the heating preset temperature of the fixing member.

1. A fixing apparatus comprising:
 a fixing member that has a base layer and a conductive layer formed therein and fixes a toner onto a recording medium when the conductive layer is heated by electromagnetic induction; 
 a magnetic field generating member that generates an alternating-current magnetic field crossing the conductive layer formed in the fixing member; and 
 a magnetic field inducing member that is arranged so as to face the magnetic field generating member across the fixing member, and that induces the alternating-current magnetic field generated in the magnetic field generating member thereinto or allows the alternating-current magnetic field to go therethrough, 
 the base layer of the fixing member and the magnetic field inducing member each containing a material having a magnetic permeability change onset temperature in the range of not less than 140 degrees and not more than 240 degrees in a temperature range from not less than a heating preset temperature of the fixing member to not more than a heatproof temperature of the fixing member, and a thickness of the base layer being smaller than a skin depth of the base layer at the heating preset temperature of the fixing member. 
 
     
     
       2. The fixing apparatus according to  claim 1 , wherein
 the magnetic field inducing member is spaced from the fixing member by a predetermined distance. 
 
     
     
       3. The fixing apparatus according to  claim 2 , wherein
 the magnetic field inducing member has an eddy current dividing part formed therein, the eddy current dividing part dividing an eddy current generated by the alternating-current magnetic field generated in the magnetic field generating member. 
 
     
     
       4. The fixing apparatus according to  claim 2 , wherein
 the magnetic field inducing member contains a material having a magnetic permeability change onset temperature below the magnetic permeability change onset temperature of the base layer of the fixing member. 
 
     
     
       5. The fixing apparatus according to  claim 1 , wherein
 the magnetic field inducing member is arranged in contact with the fixing member. 
 
     
     
       6. The fixing apparatus according to  claim 5 , wherein
 the magnetic field inducing member contains a material having a magnetic permeability change onset temperature above the magnetic permeability change onset temperature of the base layer of the fixing member. 
 
     
     
       7. An image forming apparatus comprising:
 a toner image forming unit that forms a toner image; 
 a transfer unit that transfers the toner image formed by the toner image forming unit onto a recording medium; and 
 a fixing unit that fixes, onto the recording medium, the toner image transferred onto the recording medium, 
 a fixing unit including:
 a fixing member that has a base layer and a conductive layer formed therein and fixes a toner onto a recording medium when the conductive layer is heated by electromagnetic induction; 
 a magnetic field generating member that generates an alternating-current magnetic field crossing the conductive layer formed in the fixing member; and 
 a magnetic field inducing member that is arranged so as to face the magnetic field generating member across the fixing member, and that induces the alternating-current magnetic field generated in the magnetic field generating member thereinto or allows the alternating-current magnetic field to go therethrough, 
 
 the base layer of the fixing member and the magnetic field inducing member each containing a material having a magnetic permeability change onset temperature in the range of not less than 140 degrees and not more than 240 degrees in a temperature range from not less than a heating preset temperature of the fixing member to not more than a heatproof temperature of the fixing member, and 
 a thickness of the base layer being smaller than a skin depth of the base layer at the heating preset temperature of the fixing member. 
 
     
     
       8. The image forming apparatus according to  claim 7 , wherein
 the fixing unit includes the magnetic field inducing member spaced from the fixing member by a predetermined distance. 
 
     
     
       9. The image forming apparatus according to  claim 8 , wherein
 the fixing unit includes the magnetic field inducing member having an eddy current dividing part formed therein, the eddy current dividing part dividing an eddy current generated by the alternating-current magnetic field generated in the magnetic field generating member. 
 
     
     
       10. The image forming apparatus according to  claim 7 , wherein
 the fixing unit includes the magnetic field inducing member arranged in contact with the fixing member. 
 
     
     
       11. The image forming apparatus according to  claim 7 , wherein
 the fixing unit includes the magnetic field inducing member containing a material having a magnetic permeability change onset temperature below the magnetic permeability change onset temperature of the base layer of the fixing member.